docs: def dicom_to_nifti(dicom_input, output_file=None):
      """
      This is the main dicom to nifti conversion function for ge images.
      As input ge images are required. It will then determine the type of images and do the correct conversion
  
      :param output_file: filepath to the output nifti
      :param dicom_input: directory with dicom files for 1 scan
      """
  
      assert common.is_siemens(dicom_input)
  
      if _is_4d(dicom_input):
          logger.info('Found sequence type: MOSAIC 4D')
          return _mosaic_4d_to_nifti(dicom_input, output_file)
  
      grouped_dicoms = _classic_get_grouped_dicoms(dicom_input)
      if _is_classic_4d(grouped_dicoms):
          logger.info('Found sequence type: CLASSIC 4D')
          return _classic_4d_to_nifti(grouped_dicoms, output_file)
  
      logger.info('Assuming anatomical data')
      return convert_generic.dicom_to_nifti(dicom_input, output_file)